(a) Typical synthesis

of CdSe/ZnS QDs in high temperature and cosolvent. (b) Synthesis of amphiphilic polymer: cross-linking PAA and OA by EDC. (c) Phase transfer of QDs from hydrophobic phase to hydrophilic phase by stirring and sonication. (d) Reaction scheme for coupling targeting antibody to PQDs by EDC. (e) Single molecule labeling and cell imaging with PQDs in vitro. (f) General labeled cancer cell with PQDs for imaging in vitro and in vivo. Methods Materials Cadmium oxide (CdO, AR), stearic acid (98%), selenium powder, octylamine (OA, 99%), 1-hexadecylamine (HAD, 90%), and diethylzinc (ZnEt2) were obtained from Aladdin Co., Ltd. (Xi’an, China). Trioctylphosphine oxide (TOPO, 98%), trioctylphosphine (TOP, 95%), poly(acrylic acid) (PAA, molecular weight (MW) 1,800), 1-ethyl-3-[3-dimethylaminoporpyl] carbodiimide hydrochloride (EDC, 98.5%), and N-hydroxysuccinimide BAY 11-7082 (NHS, 98%) were obtained from Sigma-Aldrich Co., Ltd. (St. Louis, MO, USA). Bovine serum albumin Selleck GW3965 (BSA, 99.9%) was purchased from MP Biomedicals Company (Santa Ana, CA, USA). Bis(trimethylsilyl) sulfide ((TMS)2S) was purchased from Tokyo QNZ solubility dmso Chemical Industry Co., Ltd. (Tokyo, Japan). Liquid paraffin, chloroform, ethanol, hydrochloric acid (HCl), 2-(4-morpholino)ethanesulfonic acid (MES), N,N-dimethylformamide

(DMF), paraformaldehyde, and Tween-20 were purchased from Sinopharm Chemical Regent Co., Ltd. (Shanghai, China). Synthesis of CdSe and CdSe/ZnS core-shell QDs Highly luminescent core-shell CdSe/ZnS QDs were prepared in high temperature via the pyrolysis of organometallic reagents in a coordinating solvent [26–28]. We select 200°C with and without HAD for synthesis of green- and red-emitting CdSe QDs. The molar ratio of CdO/Se/stearic acid in liquid paraffin was 1:1:4, and the crude QD products were purified by chloroform and ethanol. For the ZnS shell, equal molar ratios of (TMS)2S

and ZnEt2 as precursors of Zn and S, and TOP/TOPO were used, and 90°C was used for shell growth. 2-hydroxyphytanoyl-CoA lyase The final core-shell product was repurified and redispersed into aliquot chloroform for later use. About 10 ml of deionized water was added to the solution to prevent evaporation of chloroform for long-period storage (see Additional file 1 for synthesis details of QDs). Synthesis and characterization of amphiphilic polymer The amphiphilic polymer is synthesized as follows: in ambient temperature, 0.2 g of PAA (MW 1,800) was added to a flask containing 10 ml DMF. Under slight stirring for 1 h, 137 μl of OA was added, and the solution was continuously stirred for another 30 min. In an individual vial, 0.47 g EDC was dissolved in 0.5 ml DMF and injected to the reaction solution dropwisely. The reaction solution was mixed vigorously overnight to produce amphiphilic polymers (with 50% of the carboxylic acid functional groups modified with an aliphatic chain). Next, 0.25 M HCl was added drop by drop to the polymer solution under vigorous stirring, resulting in a milky and opaque colloid solution.